Sea Ice Index, Version 1

Version 1 of the Sea Ice Index is no longer available and has been replaced with Version 2. Please see the Version 2 record to obtain that data.

The Sea Ice Index provides a quick look at Arctic- and Antarctic-wide changes in sea ice. It is a source for consistent, up-to-date sea ice extent and concentration images, in PNG format, and data values, in ASCII text files, from November 1978 to the present. Sea Ice Index images also depict trends and anomalies in ice cover calculated using a 30-year reference period of 1981 through 2010.

The images and data are produced in a consistent way that makes the Index time-series appropriate for use when looking at long-term trends in sea ice cover. Both monthly and daily products are available. However, monthly products are better to use for long-term trend analysis because errors in the daily product tend to be averaged out in the monthly product and because day-to-day variations are often the result of short-term weather.

Monthly extent products are also available as geographic information systems (GIS) compatible shapefiles.Data are available via FTP.

海冰指数（Sea Ice Index）V1版本现已不再提供，并已由V2版本取代。请查阅V2版本的数据记录以获取相关数据。

海冰指数可快速呈现全球北极与南极海域的海冰变化情况。该数据集提供了自1978年11月至今的标准化、最新海冰范围与海冰密集度图像（PNG格式），以及对应的数据值（ASCII文本文件）。海冰指数图像还展示了以1981至2010年为30年参考时段计算得到的海冰覆盖变化趋势与异常值。

所有图像与数据均采用统一标准生成，使得该指数的时间序列适用于海冰覆盖长期趋势分析。数据集同时提供月度与逐日两类产品。不过，进行长期趋势分析时更推荐使用月度产品：一方面逐日产品的误差可在月度产品中被平均抵消，另一方面海冰的逐日变化往往由短期天气过程主导。

月度海冰范围产品还提供兼容地理信息系统（GIS）的形状文件格式。数据可通过FTP获取。